[FFmpeg-cvslog] [ffmpeg] avcodec/nvdec: fix surface pool limits and unsafe_output lifetime (branch master)

[Diego de Souza via ffmpeg-cvslog]

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Git pushed a commit to branch master
in repository ffmpeg.

The following commit(s) were added to refs/heads/master by this push:
     new 6ef0ef51dc avcodec/nvdec: fix surface pool limits and unsafe_output 
lifetime
6ef0ef51dc is described below

commit 6ef0ef51dc1ba58e3fd6929e201e1c2cd15198b6
Author:     Diego de Souza <ddeso...@nvidia.com>
AuthorDate: Mon Mar 16 00:14:42 2026 +0100
Commit:     Timo Rothenpieler <t...@rothenpieler.org>
CommitDate: Mon Mar 16 18:18:12 2026 +0000

    avcodec/nvdec: fix surface pool limits and unsafe_output lifetime
    
    Cap ulNumDecodeSurfaces to 32 and ulNumOutputSurfaces to 64 to prevent
    cuvidCreateDecoder from failing with CUDA_ERROR_INVALID_VALUE when
    initial_pool_size exceeds the hardware limits.
    
    Also cap the decoder index pool (dpb_size) to 32 so that indices
    handed out via av_refstruct_pool_get stay within the valid range
    for cuvidDecodePicture's CurrPicIdx.
    
    When unsafe_output is enabled, stop holding idx_ref in the unmap
    callback. Since cuvidMapVideoFrame copies decoded data into an
    independent output mapping slot, the decode surface index can safely
    be reused as soon as the DPB releases it, without waiting for the
    downstream consumer to release the mapped frame. This decouples the
    decode surface index lifetime (max 32) from the output mapping slot
    lifetime (max 64), eliminating the "No decoder surfaces left" error
    that occurred when downstream components like nvenc held too many
    frames.
    
    Signed-off-by: Diego de Souza <ddeso...@nvidia.com>
---
 libavcodec/nvdec.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/libavcodec/nvdec.c b/libavcodec/nvdec.c
index 7c29f25718..60becd2733 100644
--- a/libavcodec/nvdec.c
+++ b/libavcodec/nvdec.c
@@ -413,8 +413,8 @@ int ff_nvdec_decode_init(AVCodecContext *avctx)
     params.OutputFormat        = output_format;
     params.CodecType           = cuvid_codec_type;
     params.ChromaFormat        = cuvid_chroma_format;
-    params.ulNumDecodeSurfaces = frames_ctx->initial_pool_size;
-    params.ulNumOutputSurfaces = unsafe_output ? frames_ctx->initial_pool_size 
: 1;
+    params.ulNumDecodeSurfaces = FFMIN(frames_ctx->initial_pool_size, 32);
+    params.ulNumOutputSurfaces = unsafe_output ? 
FFMIN(frames_ctx->initial_pool_size, 64) : 1;
 
     ret = nvdec_decoder_create(&ctx->decoder, frames_ctx->device_ref, &params, 
avctx);
     if (ret < 0) {
@@ -438,7 +438,7 @@ int ff_nvdec_decode_init(AVCodecContext *avctx)
         ret = AVERROR(ENOMEM);
         goto fail;
     }
-    pool->dpb_size = frames_ctx->initial_pool_size;
+    pool->dpb_size = FFMIN(frames_ctx->initial_pool_size, 32);
 
     ctx->decoder_pool = av_refstruct_pool_alloc_ext(sizeof(unsigned int), 0, 
pool,
                                                     nvdec_decoder_frame_init,
@@ -543,7 +543,6 @@ static int nvdec_retrieve_data(void *logctx, AVFrame *frame)
         goto copy_fail;
 
     unmap_data->idx = cf->idx;
-    unmap_data->idx_ref = av_refstruct_ref(cf->idx_ref);
     unmap_data->decoder = av_refstruct_ref(cf->decoder);
 
     av_pix_fmt_get_chroma_sub_sample(hwctx->sw_format, &shift_h, &shift_v);

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